Crucible former and sprue former carrier



Oct. 24, 1961 E. A. STEINBOCK ETAL 3,005,232

CRUCIBLE FORMER AND SPRUE FORMER CARRIER Filed Dec. 6, 1954 INVENTORfi Eonuuo A. srsuvaocx, Cum. flRMoREcHT,

Eomuun A STE/Meow JR.,

fluorye United States Patent 3,005,232 CRUCBLE FGRMER AND SPRUE FOR CARRIER Edmund A. Steinbeck, 333 Shawnee Terrace, Louisville,

Ky, and Charles Armbrecht and Edmund A. Steinhock, In, Louisville, Ky; said Annbrecht and said Steinbock, in, assignors to said Steinbeck Original application Apr. 23, 1951, Ser. No. 222,372. Divided and this application Dec. 6, 1954, Ser. No.

Claims. (Cl. 18--5.7)

This invention relates to improvements in a crucible former and sprue former carrier for use with investment mixers and particularly where the mixing and investing is accomplished ina sub-atmospheric environment or in a vacuum.

This application is a division of pending application Serial No. 222,372 for Investment Mixers, filed April 23, 1951, now US. Patent No. 2,696,022.

This invention relates to. improvements in investment mixers over that disclosed in the pending application of Elizabeth A. Luster, Robert Neirnan and Edmund A. Steinbock, In, Serial No. 200,182, now abandoned, filed December 11, 1950.

The invention of the present application corrects defects existing in prior structures in so far as the prevention of leakage is concerned in investment mixers that are operated while the interior thereof and the interior of the casting ring or mold forming housing is under vacuum.

The principal object of the present invention, therefore, is the provision of a crucible former and sprue former carrierwhich, while usable with any casting ring or mold forming housing, is particularly adaptable for use with investment mixers of the, so called, vacuum type.

' Another object of the present invention is the provision of a crucible former and sprue former carrier which while formed of flexible material will not be deformed when under pressure, as when the interior of a casting ring or mold forming housing is subjected to subatmospheric pressure, and therefore will prevent leakage when in use.

A still further object of the present invention is the provision of a crucible former and sprue former carrier formed in the main of flexible elastic material that is reinforced by non-flexible material which prevents its deformation when in use and under vacuum pressure.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings forming a part thereof and it is to be understood that any modifications may be made in the exact structural details there shown and described, Within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

In the drawings:

FIG. 1 is an elevational view of an investment mixer embodying the principles of the present invention.

FIG. 2 is a top plan view of the mixer mechanism as disclosed in FIG. 1.

' FIG. 3 is a vertical sectional view through the mixer as seen from line 3-3 on FIG. 2.

FIG. 4 is a horizontal sectional view through the crucible former and sprue former carrier as seen from line 4-4 on FIG. 3.

' Throughout the several views of the drawings similar reference characters are employed to denote the same or similar parts.

Investment mixers are employed in industry in the mixing of powders and liquid into a flowable plastic for the making of molds which are subsequently destroyed 3,005,232 Patented Ofct. 24, 1961 plicable to the larger commercial use. The main reason for providing a device whereby the materials are mixed in a vacuum is to extract all air from the mixture so that a smooth unbroken mold surface is provided and so that the resulting casting has a smooth surface free of cavities or nodules.

As noted above, in the past certain difficulties were encountered which resulted in certain defects in the mold and the resulting casting even though the process of male ing the mold and the casting was carried out in subatmospheric conditions or within a vacuum. This was caused due to leakage in certain relatively extraneous parts which of necessity were made of rubber and which parts, therefore, distorted during the process. In order that the invention be thoroughly understood one form of an investment mixer is disclosed in the drawings and will be described in detail.

Accordingly, and as disclosed in the drawing, use is made of a bowl 10 illustrated as formed of rubber and having a bottom 11 from which the sides 12 outwardly and upwardly flare to an open top bounded by a rim 13. The open top of the bowl 10 is closed by a top or cover 14, in eflect, a recessed flat disc having a radial flange 15. The body portion 16 of the top or cover 14 depends into the bowl rim 13, with the periphery of the said body portion 16 inwardly and downwardly tapered, as at 17, to have a snug fit with the bowl rim 13. The top or cover 14 has upstanding therefrom, at substantially its center, a boss 18 which, as seen in FIG. 2, has its longitudinal axis outwardly radiating from the top or cover center. The boss 18 is provided at substantially the top or cover center with an aperture 19 into which is pressed a bearing sleeve 29 acting as a journal for the enlarged bearing portion 21 of a driven shaft, indicated in its entirety by the reference numeral 22.

The driven shaft 22 has depending from its bearing portion 21 a reduced portion 23 to which is attached a mixer blade or paddle 24. Any suitable or desirable method or means may be employed for securing the mixer blade or paddle to the driven shaft 23 that shown consisting of forming transversely of the blade or paddle a plurality of slits 25 between the upper and lower ends thereof and outwardly and oppositely pressing the material on opposite sides of each slit 25 to thereby form semi-circular sleeves 26 extending from the opposite surfaces of the blade or paddle with adjacent semi-circular sleeves together forming a complete sleeve and providing a substantially central passageway through said blade through which the shaft portion 23 passes. The driven shaft 22 passes upwardly of the bearing sleeve 20* for attachment to any suitable or desirable means for effecting its rotation and the rotation of the mixing blade or paddle 24.

The top or cover 14 is provided therethrough, and to one side of the axial center thereof, with a passageway 27 which has its axis preferably, but not necessarily, angularly related to the vertical axis of the bowl 10. Dis posed in the passageway 27 is a sleeve 28 receiving one end 29 of a fitting 30 which has its other end, outwardly of the sleeve 28, ridged or stepped as at 31 for the reception of a flexible hose or conduit, not shown. The end 29 of the fitting 30 has a leak-proof joint with the sleeve 28 and the flexible hose or conduit, not shown, has its other end connected with a vacuum pump or motor, likewise not shown.

The cover or top 14 is provided to one side of its axial center with a laterally and upwardly extending boss 32 which extends beyond the rim of the cap or cover flange 15, as shown most clearly in FIGS. 2 and 3. The boss 32 is provided with a plurality of concentric counterbores each terminating in a seat with the innermost counterbore terminating in the seat 33 forming the base of the counterbores and through which extends a passageway or bore 34 into the interior of the bowl 10. The said passageway 34 through the body portion 16 of the top or cover 14 simulates an inverted funnel, as at 35, and acts as a funnel for a purpose subsequently to be made clear. Disposed within the counterbores andresting on the counterbores lowermost seat or base 33 is one end of a casting ring or mold forming housing 36. The other end of the casting ring or mold forming housing 36 is closed by a member 37, known in the trade as a crucible former and sprue former carrier, and which forms the subect matter of the present invention.

In operation the ingredients to be mixed, plaster of Paris, or the like, water, accelerators, retarders, and other desirable ingredients, are disposed in the bowl 10 and are then hand spatulated or not, as desired, whereupon the top or cover 14 is placed on the bowl for closing the same. The reason for hand spatultion is to wet down the dry ingredients and prevent withdrawal thereof by the vacuum pump or motor. The casting ring or mold forming housing is then disposed in the boss 32, the said casting ring or mold forming housing having had prevously attached thereto the crucble former 37. The fitting 30, with its flexible hose or conduit attached, is then inserted in the sleeve 28 and the vacuum pump or motor operated for drawing air from the interior of the bowl 10 as well as fromthe interior of the casting ring or mold'forming housing 36. The shaft 22 is now rotated for thoroughly mixing the ingredients within the bowl 10. It will be understood that as the mixing blade or paddle 24 is rotated the ingredients are tumbled about, pressed against one another, and otherwise thoroughly intermixed with one another thereby releasing or liberating any air that may have been introduced into the bowl with the ingredients, or entrapped by the ingredients, and that all such liberated air is drawn off by the vacuum pump or motor.

7 In order that there be no leakage or communication with the atmosphere, each of the openings through the top or cover 14 is provided with a seal which may take any suitable or desirable form, preferably that shown in the drawings. As illustrated in FIG. 3 the leak-proof joint of the reduced end 29 of the vacuum hose fitting 30 is accomplished by providing the said fitting reduced end 29, intermediate its ends, with a circumferental groove 38 in which is disposed a gasket 39 known in the trade as an ring. An 0 ring is, as its name implies, a circle of compressible material, preferably rubber, and preferably having a circular transverse cross-section, which when mounted in the groove 38 has its outer edge projecting sufliciently beyond the outer surface of the fitting that when inserted in the sleeve 28 the 0 ring is transversely compressed thereby providing a leak-proof joint between the fitting reduced end 29 and sleeve 28.

The mixing paddle or blade shaft 22 is similarly sealed and for which purpose the bearing portion 21 is provided intermediate its ends with a circumferential groove 40 for a gasket or O ring 41 which bears the same relation to the said shaft bearing portion 21 and its journal or bearing sleeve 19 as above set forth with respect to the O ring 39 for thereby effecting a leak-proof seal around the said shaft bearing.

The casting ring or mold forming housing 36 is likewise sealed by an O ring, but since the casting ring or mold forming housing 36 is of considerably greater size than the fitting 30 or shaft bearing 21, and since the casting ring or mold forming housing must be inserted and removed from its counterbore, the force necessary in compressing the 9 ring 42 rendered it difiicult to follow the same procedure as above set forth in connection with the 0 rings 39 and 41. As disclosed in FIG. 3, and as noted above, the boss 32 is provided with a plurality of concentric counterbores each of which terminates in a seat which may be designated as a lower intermediate seat 43, an upper intermediate seat 44, and an uppermost seat 45. Prior to the insertion of the casting ring or mold forming housing into the boss 32 the 0 ring 42 is disposed within the counterbore and on the upper intermediate seat 44. The casting ring or mold forming housing 36 is initially brought into engagement with the 0 ring 42 while the said 0 ring 42 is on said upper intermediate seat 44 with no appreciable effort made to push the casting ring into the 0 ring and as the vacuum within the bowl is established the said vacuum. draws the casting ring to its seat 33 thereby forcing the ring 36 through the 0 ring- 42 and at the same time. rolling the 0 ring down onto the lower intermediate counterboreseat 43. and at the same time compressing the O ring 42, as clearly illustrated in FIG. 3, betweenthe outer surface of the casting ring and the surface of the counterbore. The counterbores of the boss 32 are closed by a guide ring 46 disposed on the counterbores uppermost seat45, the guide ring 46 acts as a guide for the casting ring 36 when initially placed against the 0 ring gasket 42 and at the same time prevents the disassociation of the 0 ring 42 from the boss 32 as will presently be made clear.

In the past the crucible former and sprue former carrier 37 were cast of rubber, as the said part of the present invention is formed, but the vacuum within the bowl 10 and casting ring or mold forming housing 36 had a tendency to inwardly draw the body portion47 thereby causing the pulling away of the lip 48 of the crucible former from the casting ring and permitting communication with the atmosphere. As disclosed in FIG. 3 the said crucible former 37 has imbedded'in its outer end a metal plate 49 whichresists any" flexing in the crucible former and thereby prevents the'lip 48 from being outwardly flexed from the casting ring.

The plate 49' is, preferably, of a diameter equal to or slightly greater than the interior diameter of the casting ring or mold forming housing and has its periphery 61 embedded in the body portion 47 and underlying lips 62 and 63 of said body portion. The plate 49 is further provided centrally thereof with an aperture 64 into which projects a boss 65 the crucible former and sprue former carrier body portion. In addition, the plate 49 is convexly formed between its central aperture 64 and periphery 61, as indicated at 66, with its said periphery in contact with the shoulder formed by the lip 6263 and the periphery of its central aperture in contact with the boss 65.

With this construction the body portion 47 is restrainedagainst flexing since the pressure within the casting ring or mold forming housing would have to be such as to straighten out the convexity of the plate, which in itself would require a great pressure, and at the same time cause the peripheral edge of the plate and the central aperture to cut into the said body portion beneath the lips 62 and 63 and cut into thesaid body portion boss 65. i i

The bowl 1t) and casting ring 36 now being air tight the shaft 22 is rotated by any suitable or desirable means.

As disclosed in the drawings, one rneans for. rotating the shaft 22 consists in forming integrally with the said shaft 22 above the bearing portion 21 a pinion 50 meshing with a gear 51 integral with or secured to a driving shaft 52. The pinion 5i and gear 51 are disposed in a recess 53 formed downwardly of the upper surface ofthe housing boss 18. The recess 53 is closed by a cap 54 secured to the boss 18 by suitable cap screws 55. The cap 54 is provided with hearing sleeves for the upper end' of the driven and driving shafts such as the bearing sleeve 56 for the driven mixer blade or paddle shaft 22. 'The shaft 52 projects upwardly through the cap 54 to have its upper end above the casting ring or mold forming housing 36 and crucible former 37, and to which projecting end is secured, by a screw 58, one end of a lever or crank 59. The other end of the crank or lever 59 is provided with an actuating knob or handle 60.

After the ingredients have been sufliciently intermixed, the bowl l0 and parts carried thereby, while the vacuum pump or motor is in operation, is turned in a clockwise direction, as seen in FIG. 3, onto a vibrator, not shown, and with the crucible former 37 resting on the plate of the said vibrator. The mixed ingredients, now in a flowable plastic state, are, by the action of the vibrator, brought to the funnel 35 which directs the same to and through the passage 34 into the casting ring or mold forming housing 36 to encase the pattern 67 and sprue former 68 extending from the said pattern and carried by a socket 69 in the crucible former and sprue former carrier 37. The bowl is turned in a clockwise direction to a point not quite vertical so that the mixed ingredients will flow to the said funnel 35 rather than be disposed on the under side of the top or cover 14 as would be the case if a complete inversion of the bowl from the position of FIG. 3 were made.

After the casting ring or mold forming housing 36 has been filled the vacuum pump or motor is stopped and the fitting 30 removed from the sleeve 28 thereby breaking the vacuum within the bowl 10. The casting ring or mold forming housing 36 is now axially withdrawn irom the boss 32. The connection of the 0 ring 42 is such that the casting ring or mold forming housing 36 is readily withdrawn and in so doing rolls the O ring 42 from its position on the counterbore lower intermediate seat 43 of FIG. 3 to a position on the upper intermediate seat 44 whereupon the compression in the O ring 42 is reduced to substantially zero allowing the ready separation of the parts.

From the foregoing it will be noted that there has been provided for an investment mixer operating in a vacuum a closure, crucible former and sprue former carrier, that is especially adapted for such use to prevent leakage and otherwise tend to insure more accurate and eflicient investment mixing and resulting casting.

What is claimed is:

1. A crucible former and sprue former carrier for a cementitious mold forming housing wherein the mold forming housing is ring-like in plan, comprising a body portion circular in plan and provided with a groove inward-1y of its periphery receiving the mold forming housing, said crucible former and sprue former carrier being formed of flexible material, and an inflexible plate within body portion of the crucible former and the sprue former carrier of an area substantially equal to the area of the mold forming housing bore, said inflexible plate being formed convexo-concavo in the direction of the groove in the crucible former and sprue former carrier body portion.

2. The combination of a sleeve-like cementitious mold forming housing, and a crucible former and sprue former carrier comprising a body portion of an area in excess of the area of the mold forming housing, said crucible former and sprue iformer carrier body portion having formed inwardly of its periphery a continuous groove receiving one end of the mold forming housing, a projection from the crucible former and sprue former carrier body portion inwardly of the groove to project into the mold forming housing, a flange outwardly of the groove for embracing the said end of the mold forming housing, said crucible former and sprue former carrier being formed of flexible material, an inflexible plate within the body portion of the crucible former and sprue former carrier rendering the said body portion inflexible, said inflexible plate having an area, at least, substantially equal to the interior of the mold forming housing, and cooperating means on the plate and crucible former and sprue former carrier for retaining said plate within said body portion.

3. The combination of a sleeve-like cementitious mold forming housing, and a crucible former and sprue former carrier comprising a body portion of an area in excess of the area of the mold forming housing, said crucible former and sprue former carrier body portion having formed inwardly of its periphery a continuous groove receiving one end of the mold forming housing, a projection from the crucible former and sprue former carrier body portion inwardly of the groove to project into the mold forming housing, a flange outwardly of the groove for embracing the said end of the mold forming housing, said crucible former and sprue former carrier being formed of flexible material, and an inflexible plate within the body portion of the crucible former and sprue former carrier rendering the said body portion inflexible, said inflexible plate having an area, at least, substantially equal to the interior of the mold forming housing and central 1y apertured, and said plate being outwardly curved between its central aperture and periphery.

4. A crucible former and sprue former carrier for a cementitious mold forming housing, comprising a body portion circular in plan and provided with a groove inwardly of its periphery adapted to receive a mold forming housing, said crucible former and spnue former carrier being formed of flexible material, a flange upstanding from said body portion outwardly of the groove, said crucible former and sprue former carrier having a flat lower surface and a recess upwardly of said lower surface, said recess having a flange inwardly projecting from its periphery, and an inflexible plate within said recess retained in operative position by said recess peripheral flange.

5. A crucible former and sprue former carrier for a cementitious mold forming housing, comprising a body portion circular in plan and provided with a groove inwardly of its periphery adapted to receive a mold forming housing, said crucible former and sprue former carrier being formed of flexible material, a flange upstanding from said body portion outwardly of the groove, said crucible former and sprue former carrier having a flat lower surface and a recess upwardly of said lower surface, said recess having a flange inwardly projecting from its periphery, said recess having a base with a centrally located outwardly projecting lug and said base outwardly arched between the lug and recess periphery, and an inflexible plate having a central aperture and a concaved formation outwardly of the aperture disposed on said lug in intimate contact with the recess base and its periphery underlying the recess peripheral flange.

References Cited in the file of this patent UNITED STATES PATENTS 1,193,645 Weinstein Aug. 8, 1916 1,518,521 Kraft Dec. 9, 1924 2,334,078 Feinberg Nov. 9, 1943 2,507,867 Pomes May 16, 1950 2,606,347 Hildreth Aug. 12, 1952 

